In a manufacturing process of a semiconductor device or an LCD substrate, a resist pattern is formed on a substrate by using a photolithography technology. This technology includes a series of processes of coating a resist liquid on the substrate such as a semiconductor wafer (hereinafter, referred to as ‘wafer’), forming a liquid film on the surface of the wafer, exposing the resist film by using a photo mask and then developing it.
Such processing is generally performed by using a resist pattern forming apparatus including a coating/developing device and an exposure device connected thereto as configured in, e.g., Japanese Patent Laid-open Publication No. 2004-193597. In such an apparatus, as shown in FIG. 12, a carrier 10 containing a plurality of wafers W is loaded in a carrier stage 11 of a carrier block 1A and a wafer in the carrier 10 is transferred to a processing block 1B by a transfer arm 12. Subsequently, the wafer is transferred to a coating unit 13A in the processing block 1B where the resist liquid is coated thereon, and then transferred to an exposure device 1D via an interface block 1C. After having undergone an exposure processing, the wafer is back transferred to a developing unit 13B in the processing block 1B where a developing process is performed thereon, and then returned to the original carrier 10. Reference numerals 14a to 14c in the drawing represent rack units each of which is provided with a heating unit and a cooling unit for respectively heating and cooling the wafer before or after the processing by the coating unit 13A or the developing unit 13B and transfer stages.
Here, the wafer W is transferred by two transfer units 15A and 15B between modules where the wafer W is placed in the processing block 1B, namely, the coating unit 13A, the developing unit 13B and each part of the rack units 14a to 14c. At this time, during the processing, the wafer W is transferred in accordance with a transferring schedule wherein all wafers W to be processed are determined to be transferred to predetermined modules at predetermined timings.
Conventionally, a coating/developing device has been used for forming a certain type of film exclusively, and it has been customarily accepted that another different kind of coating/developing device is expected to be used for forming a correspondingly different type of film. Recently, however, it has become a trend that a single coating/developing device is required to handle many batches, each batch including small quantity production of different kind of films. For example, as for the type of the coating film, there are a case where a bottom antireflection coating (“BARC”) is formed on the top and the bottom of the resist film, a case where the BARC is formed only on either the top or the bottom of the resist film, and a case where no BARC is formed on the resist film and it is required to develop a coating/developing device which can be applied to all of the above various cases. In this case, if the coating unit and the developing unit are provided in a same processing block, the number of units provided in a single processing block becomes great and the size of the processing block is increased, thereby resulting in a large occupancy area thereof.
Further, there may occur a trouble such as a case where the modules such as the coating unit 13A and the heating unit or the transfer units 15A and 15B provided in the processing block 1B become out of order, or the wafer W cannot be transferred at a desired time between the transfer units 15A and 15B and the respective modules. In this case, the operations of the transfer units 15A and 15B and hence the coating/developing device are stopped altogether.
When the transfer units 15A and 15B are stopped, the wafers W remain in the respective modules without being taken out. If the wafers W processed by the coating unit 13A are left in the coating unit 13A, the film quality thereof becomes deteriorated so that a desired quality of the resist film cannot be assured when the wafers W are transferred again by the transfer units 15A and 15B. Accordingly, the wafers W, which were left in the respective modules, are retrieved from the device without being used as a final product and are prepared to be recycled by cleaning the coating film thereon with a solution.
Meanwhile, a recent trend towards a faster throughput of the exposure device requires an enhanced processing capability of the coating/developing device matching with the faster throughput capability of the exposure device. To this end, the number of wafers W introduced into a line of the processing block 1B is increased, so that if there occurs a trouble in the processing block 1B, the number of wafers W to be recycled is increased. As a result, the burden of the processing such as a cleaning process, which should be performed to recycle the wafers W, becomes greater. Moreover, the device cannot be operated while retrieving the wafers W, operating for confirming the locations where the trouble occurs and performing a maintenance work, thereby deteriorating the throughput thereof.
In order to enhance the throughput of the coating/developing device, the present inventor has studied an approach for reducing the burden of the transfer units by vertically arranging an area of the modules before the exposure processing and an area of the modules after the exposure processing at up and down positions. Japanese Patent Laid-open Publication No. 3337677 discloses an arrangement in which a coating area and a developing area are vertically disposed at up and down positions and the transfer unit is provided in each of the areas.
Even in such an arrangement, there may also occur the aforementioned trouble such as the malfunction of the modules and the transfer units in the coating areas and the developing area; however, Japanese Patent Laid-open Publication No. 3337677 does not disclose any approach therefor.